Measuring Mark Audio Alpair-10 gen-2
The thread is a bit butchered as the results raised a few heated comments. But the FR graphs are on page two. If the banter doesn't make sense, it's because the mods hacked out all the objectional posts
The thread is a bit butchered as the results raised a few heated comments. But the FR graphs are on page two. If the banter doesn't make sense, it's because the mods hacked out all the objectional posts
I should add, I was pleasantly surprised by my recent MA alp6p measurement. It measures both well, and fairly close to Mark's. But I'd say the Fostex I measured is much closer to the spec sheet.
Just wanted to share in case it sounds like I'm over stating my position. And sorry to derail the topic.
Just wanted to share in case it sounds like I'm over stating my position. And sorry to derail the topic.
Interesting.
FWIW, on the basis of a quick gander (I'm, if you'll forgive the expression, 'knackered'; & heading to my bed in a minute) I suspect what these tend to illustrate is how different test gear / conditions can appear to produce different results. The FR graph on p.2 of your link for e.g. looks somewhat different from the published data, but similar to that from Klang + Ton's measurements (2011, No.2 p.56). The latter though broadly agree with the manufacturer plots when the different scales / sizes of the graphs used &c. are accounted for. Not perfect, nothing is, but the general trends are there. When I'm more awake I'll look at the PE link properly, but I suspect something similar is occurring. Incidentally, the same basic thing seems to apply to the K+T measures of Fostex & TB drivers compared to the factory plots. YMMV as always of course.
I tend to be cautious with all data, whether from the manufacturer or a 3rd party. The latter is not an automatic guarantee of being more accurate, although it may be taken & presented in a more objective fashion. With that said, they often have their own issues too. For e.g., I gather a certain magazine's test equipment (not K+T) is of a very mediocre quality, and that they don't always chamfer the driver cut-outs on their test baffles, with predictably negative results. My spies tell me that units from several manufacturers, including some rather well known European brands got hit by that one. You can imagine how pleased they were.
FWIW, on the basis of a quick gander (I'm, if you'll forgive the expression, 'knackered'; & heading to my bed in a minute) I suspect what these tend to illustrate is how different test gear / conditions can appear to produce different results. The FR graph on p.2 of your link for e.g. looks somewhat different from the published data, but similar to that from Klang + Ton's measurements (2011, No.2 p.56). The latter though broadly agree with the manufacturer plots when the different scales / sizes of the graphs used &c. are accounted for. Not perfect, nothing is, but the general trends are there. When I'm more awake I'll look at the PE link properly, but I suspect something similar is occurring. Incidentally, the same basic thing seems to apply to the K+T measures of Fostex & TB drivers compared to the factory plots. YMMV as always of course.
I tend to be cautious with all data, whether from the manufacturer or a 3rd party. The latter is not an automatic guarantee of being more accurate, although it may be taken & presented in a more objective fashion. With that said, they often have their own issues too. For e.g., I gather a certain magazine's test equipment (not K+T) is of a very mediocre quality, and that they don't always chamfer the driver cut-outs on their test baffles, with predictably negative results. My spies tell me that units from several manufacturers, including some rather well known European brands got hit by that one. You can imagine how pleased they were.
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A search on this question here and elsewhere would no doubt reveal that it's a very polemic issue - with all sorts of facts stated by both sides to buttress their own position.
Sure it's easy to find MDF that cuts and machines like butter with quality tooling, and certainly even the highest quality grade has a huge price advantage over BB or superior grades of High Density count plywood.
FWIW, I've been working in the commercial millwork trade for over 20yrs, and have had access to virtually every type of sheet goods available in North America. For the first few years of my DIY speaker building, I made most of my projects from off-cuts / waste MDF, so the price was certainly right. Then about 10(?) years ago on a dare I built two identical pairs of enclosures from 3/4" MDF and 18mm BB, and veneered both so that the only way you could tell which was which was to move them. Perhaps I credit myself too much for complete objectivity on my first listening session, but as with some other "tweaks" I've encountered along the way, the first "blind" listening session was all it took for me to reach my own conclusion. The BB was faster and tighter in the bass, with more presence and dimensionality in the soundstage.
The only material which I've personally heard to sound more musical in a direct comparison of same enclosure design is 3/4" 3 layer bamboo ply ( 1/2" stave core with 1/8" face plies stranded or edge grain - I've not actually heard the flat grain version )
I'd agree they broadly agree. And it wouldn't bother me if Mark didn't hype up his statement of "RAW" measurements. His FR plots gloss over break up and resonances very easily. So when a newcomer to the forum says "almost to good to be true" I feel the need to step in and say. It is to good to be true.
Yes.
Which tends to confirm the greater basic stiffness in the material (average MOE specs. confirm) with a higher panel Fs, Q, & quicker decay time that's easier to damp out.
That said, I do think MDF is a lot better than nothing at all & if it's a choice of that & not having a speaker, then the answer is a bit of a no-brainer.
And now I really am off to bed.
That said, I do think MDF is a lot better than nothing at all & if it's a choice of that & not having a speaker, then the answer is a bit of a no-brainer.
And now I really am off to bed.
Attachments
Thanx. CS = cross-spectrum? ie a cheapie... i don't really trust any of mine over 10k
dave
Treated??!?! The plot thickens.
I will have to decide between 10p and 12p, it is a bit hard to understand hos much more volume and macrodynamics the 12p is capable of, but the surface of the 12p is a lot bigger than the 10 so theoretically it should move a lot more air. No replacement for displacement and so on...
I will have to decide between 10p and 12p, it is a bit hard to understand hos much more volume and macrodynamics the 12p is capable of, but the surface of the 12p is a lot bigger than the 10 so theoretically it should move a lot more air. No replacement for displacement and so on...
I'm not much of a box designer, but doesn't that only apply to sealed? When using a resonator (port or horn or something) don't you need the T/S parameter to suite the bass extention and the displacement to get the SPL?
Does the 10 go deeper just not as loud?
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